Seasonal variation on nuclei concentration in large cities near

surface (< 500 m)

n

Jan	June	De
		c

Seasonal variation on nuclei concentration at higher layers of the atmosphere

(>750 m)

n

In summer eddy exchange is well developed and nuclei

are transferred to the upper atmospheric layers

In winter : dwellings heating

Jan		June		De			11
				Lecturec19. Condensation

nuclei

Size variation

1.5*10-7 <r< 2*10-6 cm Aitken nuclei

2.2*10-6 <r< 10-4 cm large nuclei

3.r> 10-4 cm giant nuclei (human hair diameter ~ 10-3 cm )

Activity of condensation nuclei depends on:

Size

Water absorptivity degree

Surface tension

Surface porosity

Spatially, concentrations are highest over industrial areas (eastern North America, central Europe, and eastern Asia) or where biomass is burned (South America, Africa, and Asia). Water-soluble inorganic species include sulphate, nitrate, and ammonium. There is also a climatologically controlled seasonal cycle, with global mean aerosol loading reaching a maximum in February and a minimum in October.

Lecture 19. Condensation	12
nuclei

Aerosol pollution over Northern India and Bangladesh

2001-12-04

The skies over Northern India are filled with a thick soup of aerosol particles all along the southern edge of the Himalayan Mountains, and streaming southward over Bangladesh and the Bay of Bengal. Notice that the air over the Tibetan Plateau to the north of the Himalayas is very clear, whereas the view of the land surface south of the mountains is obstructed by the brownish haze. Most of this air pollution comes from human activities. The aerosol over this region is notoriously rich in sulfates, nitrates, organic and black carbon, and fly ash. These particles not only represent a health hazard to those people living in the region, but scientists have also recently found that they can have a significant impact on the region's hydrological cycle and climate

Credit

Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

http://visibleearth.nasa.gov/view_rec.php?id=2309

Lecture 19. Condensation	13
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